package org.bouncycastle.crypto;

import java.lang.IllegalStateException;

/**
 * Block cipher engines are expected to conform to this interface.
 */
public interface BlockCipher
{
    /**
     * Initialise the cipher.
     *
     * @param forEncryption if true the cipher is initialised for
     *  encryption, if false for decryption.
     * @param param the key and other data required by the cipher.
     * @exception IllegalArgumentException if the params argument is
     * inappropriate.
     */
    public void init(boolean forEncryption, CipherParameters params)
        throws IllegalArgumentException;

    /**
     * Return the name of the algorithm the cipher implements.
     *
     * @return the name of the algorithm the cipher implements.
     */
    public String getAlgorithmName();

    /**
     * Return the block size for this cipher (in bytes).
     *
     * @return the block size for this cipher in bytes.
     */
    public int getBlockSize();

    /**
     * Process one block of input from the array in and write it to
     * the out array.
     *
     * @param in the array containing the input data.
     * @param inOff offset into the in array the data starts at.
     * @param out the array the output data will be copied into.
     * @param outOff the offset into the out array the output will start at.
     * @exception DataLengthException if there isn't enough data in in, or
     * space in out.
     * @exception IllegalStateException if the cipher isn't initialised.
     * @return the number of bytes processed and produced.
     */
    public int processBlock(byte[] in, int inOff, byte[] out, int outOff)
        throws DataLengthException, IllegalStateException;

    /**
     * Reset the cipher. After resetting the cipher is in the same state
     * as it was after the last init (if there was one).
     */
    public void reset();
}